How to set object property (of object property of..) given its string name in JavaScript?

Question

Suppose we are only given

var obj = {};
var propName = \"foo.bar.foobar\";

How can we set the prop

Answer 1

All solutions overid any of the original data when setting so I have tweaked with the following, made it into a single object too:

 var obj = {}
 nestObject.set(obj, "a.b", "foo"); 
 nestObject.get(obj, "a.b"); // returns foo     

 var nestedObject = {
     set: function(obj, propString, value) {
         var propNames = propString.split('.'),
             propLength = propNames.length-1,
             tmpObj = obj;
         for (var i = 0; i <= propLength ; i++) {
             if (i === propLength){
                 if(tmpObj[propNames[i]]){
                     tmpObj[propNames[i]] = value;
                 }else{
                     tmpObj[propNames[i]] = value;
                 }
             }else{
                 if(tmpObj[propNames[i]]){
                     tmpObj = tmpObj[propNames[i]];
                 }else{
                     tmpObj = tmpObj[propNames[i]] = {};
                 }
             }
         }
         return obj;
     },
     get: function(obj, propString){
         var propNames = propString.split('.'),
             propLength = propNames.length-1,
             tmpObj = obj;
         for (var i = 0; i <= propLength ; i++) {
             if(tmpObj[propNames[i]]){
                 tmpObj = tmpObj[propNames[i]];
             }else{
                 break;
             }
         }
         return tmpObj;
     }
 };

Can also change functions to be an Oject.prototype method changing obj param to this:

Object.prototype = { setNested = function(){ ... }, getNested = function(){ ... } } 

{}.setNested('a.c','foo')